Apparatus for examining the inner surface of pipes

ABSTRACT

Apparatus for circumferentially scanning the inner surface of a pipe by means of a television camera and for displaying the image on a monitor outside of the pipe includes a rollable carriage adapted to be pushed in the pipe, means for driving the carriage axially of the pipe, a television camera conveyed by the carriage, a camera head including a window on one side thereof and rotatably mounted on the camera, a source of light contained in the camera head to illuminate the inner surface of the pipe through the window, a reflective mirror disposed in the camera head at an angle with respect to the optical axis of the lens of the television camera so as to receive the light reflected from the inner surface through the window and to reflect the light toward the lens of the camera, means to rotate the camera head about the optical axis and means for converting the photographic image into an electrical signal which is sent to the monitor.

United States Patent [191 Hara et al.

[451 Sept. 25, 1973 [75] Inventors: Atsushi Hara; .Yoshitaka Ohno, bothof Kawasaki, Japan [73] Assignee: Nippon Kokan Kabushiki Kaisha,

Tokyo, Japan [22] Filed: Feb. 25, 1972 [21] Appl. No.: 229,288

FOREIGN PATENTS OR APPLICATIONS Germany 178/DIG. 1

Primary ExaminerI-Ioward W. Britton Att0rneyFlynn & Frishauf 5 7]ABSTRACT Apparatus for circumferentially scanning the inner surface of apipe hy means of a television camera and for displaying the image on amonitor outside of the pipe includes a rollable carriage adapted to bepushed in the pipe, means for driving the carriage axially of the pipe,a television camera conveyed by the carriage, a camera head including awindow on one side thereof and rotatably mounted on the camera, a sourceof light contained in the camera head to illuminate the inner surface ofthe pipe through the window, a reflective mirror disposed in the camerahead at an angle with respect to the optical axis of the lens of thetelevision camera so as to receive the light reflected from the innersurface through the window and to reflect the light toward the lens ofthe camera, means to rotate the camera head about the optical axis andmeans for converting the photographic image into an electrical signalwhich is sent to the monitor.

9 Claims, 3 Drawing Figures APPARATUS FOR EXAMINING THE INNER SURFACE OFPIPES BACKGROUND OF THE INVENTION This invention relates to apparatusfor examining the inner surface of a pipe or tubular body.

Prior art apparatus utilized to examine the condition or absence orpresence of surface irregulalities or defects on the inner surface of apipe have been the socalled direct view type wherein the inner surfaceis viewed in the axial direction. In other words, the inner surface isviewed obliquely. Thus for example, in the case of inspecting the innersurface wall of a straight pipe, portions of the inner wall of the piperanging from a point at a definite distance from a photographic camerato a point at an infinite distance are pictured as a doughnut shapedimage with the result that although it is possible to examine surfaceirregularities or defects located relatively close to the camera it isimpossible to know the details of those remote from the camera.

To obviate thisdifficulty, it is usual to pass the camera through thepipe to be examined by pulling the camea by means of a cord or a wirethreaded through the pipe, or pushing the camera by a long rod. With thecord or wire, it takes a large amount of labor and time to thread thesame whereas with the long rod, it can not pass through a bent portionof the pipe. This is especially true in case where existing pipes in thefield which are burried in the ground are to be examined.

SUMMARY OF THE INVENTION It is an object of this invention to provide anovel self propelled apparatus for examining the inner surface of a pipewhich can be readily moved in one or the other direction axially throughthe pipe and the inner surface is scanned by a television camera so thatthe image of the surface is displayed on a monitor outside the pipe.

Another object of this invention is to provide a novel apparatus capableof not only examining continuously and circumferentially the innersurface of a pipe but also examining precisely a particular point bystopping the movement of the examining apparatus.

Still another object of this invention is to provide a novel apparatusfor examining the inner surface of a pipe capable of determining theangular position of a surface irregularity or a surface defect on theinner surface of the pipe.

Yet another object of this invention is to provide improved apparatusfor examining the inner surface of a bent pipe.

In accordance with this invention there is provided apparatus forexamining the inner surface of a pipe comprising a carriage havingrolling means and adpated to be inserted in the pipe, means for drivingthe carriage axially through the pipe, a television camera conveyed bythe carriage, a camera head including a window at one side thereof androtatably mounted on the camera, a source of light contained in thecamera head to illuminate the inner surface of the pipe through thewindow, a reflective mirror disposed in the camera head at an angle withrespect to the optical axis of the lens of the camera so as to receivethe light reflected from the inner surface through the window andreflect the light toward the lens of the camera, means to rotate thecamera head about the optical axis and means for converting thephotographic image into an electrical signal which is sent to a monitoroutside the pipe whereby the inner surface of thepipe iscircumferentially scanned and displayed on the monitor. Further providedis a source of spot light coupled to the carriage and disposed toproject a spot light in a definite direction toward a point on the innersurface of the pipe so as to produce an image of the spot light on themonitor which acts as a reference point for affirming the angle ofrotation of the camera head.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of oneembodiment of the invention wherein a television camera is directlycoupled to a carriage;

FIG. 2 shows an enlarged side view, partly in section, of anotherembodiment of this invention utilizing modified casters; and

FIG. 3 is an enlarged side view, partially in section, of the camerahead of the embodiment shown in FIG. 2.

Throughout the drawings corresponding portions are designated by thesame reference numerals.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The illustrated embodiment ofthis invention is used to examine the inner surface of a pipe 1 adaptedto convey gas or liquid. The apparatus illustrated in FIG. 1 comprises aphotographic camera 2 provided with a plurality of (four for example)wheels 4 adapted to roll along the inner surface or wall of the pipe 1and a movable carriage 3 connected to the camera 2 through a coupling13. A camera head 14 to be described later in detail is rotatablymounted on the fore end of the camera. The carriage 5 comprises aplatformS supported by at least one wheel 6 and a source of drive 7mounted on the platform 5 for driving the wheel 6. The source of drivemay be a reversible electric motor connected to a low speed clutch 10through a speed reduction gearing 9 and a high speed clutch 8. Clutches8 and 10 are operatively connected to wheel 6 through belts or chains 11and 12 respectively. High and low speed clutches 8 and 10 areselectively used so that when one of them is used the other is held inthe inoperative condition to protect belts or chains during operation ofthe carriage.

The details of camera 2 and camera head 14 will now be described withreference to FIGS. 2 and 3. In the embodiment shown in FIG. 2, thecamera 2 takes the form of a television camera which is supported by aplurality of upper and lower casters 16 each connected to the camerathrough a pair of links pivotally connected at 15 so that the camera canbe used for pipes of variable diameters. A plurality of lamps 17 aremounted on the camera to illuminate the portions of the inner wall ofthe pipe 1 in front of the camera 2. Furthermore, a small motor 18 ismounted on the fore end of the camera to drive a gear 20 through apinion 19. Gear 20 is constructed to rotate about a lens 21 for rotatingcamera head 14 having a window 22 on one side thereof. On the inside ofcamera head 14 is contained a reflective mirror 23 inclined at asuitable angle, preferably 45 with respect to the optical axis of thelens, and a lamp 24 disposed to illuminate the inner wall of the piperadially through window 22. The camera 2 is connected to a monitor, notshown, positioned outside of the pipe through a control cable (notshown).

In operation, motor 7 (FIG. 1) is energized to move axially throughpipe 1. At the same time motor 18 is energized to rotate at a low speedthe camera head 14 about the optical axis of the lens 21 through pinionl9 and gear 20. Accordingly, lamp 24 and reflective mirror 23 arerotated about the optical axis to circumferentially scan the innersurface of the pipe, thereby converting the images of successiveportions of the inner wall into corresponding electric signals throughlens 21 and a photoelectric transducer contained in the camera. Theelctric signals are displayed on a fluorescent screen or'recorded on arecording medium provided for the monitor. In this manner,irregularities or surface defects can be continuously detected. Inaddition, since the inner surface is illuminated in the axial as well asradial direction by lamps 17 and 24, stereographic images of the defectscan be formed, thus rendering easy detection thereof.

FIG. 3 shows a modified camera head in which a spot light ismounted onthe front end of the camera head for the purpose of correctlydiscriminating the position of the image displayed on the monitor. Moreparticularly, on the front end of camera head 14 is secured a stub shaft25 in the form of a bolt or screw to rotatably support a disc 27carrying a battery 28 which acts also as a counter weight and a sourceof spot light 30 which is pivotally mounted on disc 27 by a pivot pin 26to be set at a desired angle. The source of spot light 30 is connectedto battery 28 through a conductor 31 and the spot light emanated by thesource 30 is projected upon the inner wall of the pipe and is thenreflected thereby back into lens 21 through reflective mirror 23.

With this construction, even if the camera head 14 is rotated, the disc27 is held against rotation by the weight of battery 28 with the resultthat the source of spot light 30 is also held stationary to project aspot light toward the inner wall in a definite direction. Forthisreasomwhen the window 22 of camera head 14 is directed in the samedirection as the spot light, that is when the upper inner wall isphotographed, the image thereof is displayed on the monitor togetherwith the image of the spot light whereas when the camera head is rotatedto examine the other portions of the inner wall, the image of the spotlight will not be displayed on the monitor. In this manner, ht e imageof the spot light is displayed only-when the window 24 of the camerahead is directed in a particular direction so that it is possible toreadily determine the position of the inner wall being photographed orexamined by utilizing the position of the spot light as a referencepoint. It is to be understood that it is possible not only to rotate thecamera head 14 at a constant speed in a given direction but also to stopit at any desired position. Furthermore, as it is also possible to stopthe camera and camera head at any position along the longitudinal axisof the pipe, any abnormal portion of the inner wall thereof can beexamined precisely.

It should also be understood that instead of mounting the source of spotlight 30 on disc 27 on the front end of the camera head it is alsopossible to mount the source of spot light directly on the camera 2.

It is also possible to make the brightness of the spot light larger thanthat of the light from lamp-24 for the purpose of providing a referencespot which can be readily discriminated. It is possible to adjust theangle of mounting of the source of spot light so that the image of thespot light will appear on the upper edge of the display screen of themonitor. The spotlight may be colored, or may be oscillated to produce aflickering image thereof.

The modified embodiment shown in FIG. 3 operates as follows. Afterinserting camera 2 and carriage 5 into the pipe 1 (FIG. 1), drivingmotor 7 and clutches 8 and 10 are remotely controlled for examining theinner surface of the pipe by the camera and the monitor which is locatedoutside the pipe. Thus, the motor 7 is opearted to drive wheel 6 at alow speed through clutch 8 and chain 11. At the same time motor 17 isoperated to rotate the camera head 14. Consequently, the inner surfaceof the pipe is photographed while the camera is moved axially throughthe pipe at the low speed. The result of the examination is displayed onthe monitor. Whenever an abnormal condition is observed, low speedclutch 7 is switched to drive wheel 6 at an optimum speed. Motor 7 isstopped to permit precise examination of the abnormal condition and theexamining apparatus can be pulled out of the pipe by rotating the motor7 in the opposite direction. Such reversal of the rotation can also bemade when it is desired to accurately direct the camera head to theparticular portion to be precisely examined.

It will be clear that the invention is by no means limited to thespecific embodiments illustrated. For example camera 2 and the drivingmotor 7 and clutches 8 and 10 may be mounted on the same carriage. Insuch a case, two wheels which are disposed to contact the bottom surfaceof the inner wall at points above the lowest point thereof are providedso that the cable for the examining apparatus may not interfere with themovement of the carriage. It is also possible to vary the speed of therunning wheel by varying the number of revolutions of the driving motor7.

What is claimed is:

1. Apparatus for examining the inner surface of a pipe comprising:

a carriage having rolling means and adapted to be inserted in said pipe,

means for driving said carriage axially through said pipe,

a television camera conveyed by said carriage,

a camera head including a window at one side thereof and rotatablymounted on said camera,

a source of light contained in said camera head to illuminate the innersurface of said pipe through said window,

a reflective mirror disposed in said camera head at an angle withrespect to the optical axis of the lens of said television camera so asto receive the light reflected from the inner surface through saidwindow and to reflect the light toward the lens of said camera,

means to rotate said camera head about said optical axis,

a source of spot light coupled to said carriage and disposed to projecta spot light in a definite direction toward a point on the inner surfaceof said pipe so as to produce an image of said spot light on saidmonitor which acts as a reference point for affirming the angle ofrotation of the camera head and means for converting the photographicimage into an electrical signal which is sent to a monitor outside thepipe whereby the inner surface of said pipe is circumferentially scannedand displayed on said monitor.

2. The apparatus according to claim 1 wherein the means to rotate saidcamera head includes means for adjusting the speed of rotation of saidcamera head from the outside of said pipe.

3. The apparatus according to claim 1 which further includes a source oflight for illuminating the portions of the inner surface ahead of saidcamera.

4. The apparatus according to claim 1 wherein said rolling means isvariable in size.

5. The apparatus according to claim 1 wherein said carriage drivingmeans includes means for moving said carriage at different speeds.

6. The apparatus according to claim 1 wherein said carriage comprisestwo sections coupled together, one

apparatus to variable sized pipes.

1. Apparatus for examining the inner surface of a pipe comprising: acarriage having rolling means and adapted to be inserted in said pipe,means for driving said carriage axially through said pipe, a televisioncamera conveyed by said carriage, a camera head including a window atone side thereof and rotatably mounted on said camera, a source of lightcontained in said camera head to illuminate the inner surface of saidpipe through said window, a reflective mirror disposed in said camerahead at an angle with respect to the optical axis of the lens of saidtelevision camera so as to receive the light reflected from the innersurface through said window and to reflect the light toward the lens ofsaid camera, means to rotate said camera head about said optical axis, asource of spot light coupled to said carriage and disposed to project aspot light in a definite direction toward a point on the inner surfaceof said pipe so as to produce an image of said spot light on saidmonitor which acts as a reference point for affirming the angle ofrotation of the camera head and means for converting the photographicimage into an electrical signal which is sent to a monitor outside thepipe whereby the inner surface of said pipe is circumferentially scannedand displayed on said monitor.
 2. The apparatus according to claim 1wherein the means to rotate said camera head includes means foradjusting the speed of rotation of said camera head from the outside ofsaid pipe.
 3. The apparatus according to claim 1 which further includesa source of light for illuminating the portions of the inner surfaceahead of said camera.
 4. The apparatus according to claim 1 wherein saidrolling means is variable in size.
 5. The apparatus according to claim 1wherein said carriage driving means includes means for moving saidcarriage at different speeds.
 6. The apparatus according to claim 1wherein said carriage comprises two sections coupled together, one ofsaid sections carrying said camera and the other of said sectionscarrying said carriage driving means.
 7. The apparatus according toclaim 1 wherein said source of spot light is adjustably attached to saidcamera.
 8. The apparatus according to claim 1 wherein said rolling meanscomprises a plurality of casters coupled to said carriage.
 9. Theapparatus according to claim 8 wherein said rolling means includes anadjustable link mechanism coupling said casters to said carriage foradjusting said appaRatus to variable sized pipes.